The present invention relates to a filter media in the form of a pleated cylindrical cartridge, which is located in a tank for filtering a liquid or a gas flow. The filter media defines a plurality of radially extending pleats and the inner extremities of the pleats define a cylindrical interior chamber, wherein a cylindrical tubular retainer or core is located at the inner ends of the pleats. End caps are located at the ends of the cartridge. The cleaning of such cartridges is not easy and they are frequently changed and dumped. Such filtering systems are very expensive.